The present invention relates to a hydraulic device comprising two hydraulic actuators, in particular a motor and a double-acting jack, each comprising two couplings for the entry and/or the exit of a control fluid. Two pipes are coupled to the two actuators and devised so that one conveys a pressurized fluid to a respective coupling of each actuator whilst the other discharges the fluid to the other respective coupling, and vice versa, in such a way that one of the actuators, in particular the jack, can be controlled so as to selectively produce a movement in one direction as well as in a reverse direction. A selective reversing gate is provided for reversing between the two pipes the supplying of pressurized fluid and the discharging of the fluid, so as to control the direction of the movement of one of the actuators, in particular of the said jack.
A device of the kind can consist of a rig intended in particular for agricultural, civil engineering or military works, in which the reversing gate is a control available to an operator of the rig, for example by way of a lever or of a pedal. In this kind of rig, two pipes are often installed in reserve mode to control an optional accessory which may be mounted at the tip of an articulated arm.
An exemplary case of such an optional accessory is a coring or drilling apparatus which is equipped with a hydraulic motor for rotating a drill bit and with a double-acting hydraulic jack or with another hydraulic motor for imparting to the bit a drilling advancing movement and a retreating movement of the bit.
In this exemplary case, given that only two pipes are available for the accessory, the jack and the motor must be coupled in parallel to them in such a way that, while powering the jack for an advancing movement of the bit, the motor rotates in a drilling direction. Consequently and automatically, upon powering the jack in a direction of retreat of the bit, the motor is caused to rotate in the direction reverse to the drilling direction and this is especially undesirable. The aim of the present invention is to remedy in particular this problem and to provide in this case, as in others not described at present, a simple and effective means which makes it possible, on the one hand, to procure in a known manner the advancing and retreating movement of the jack and, on the other hand, to have the motor of the bit retain the same direction of rotation during both the advancing and retreating movements, without adding further pipe(s) to an existing rig.
Accordingly, the invention consists in equipping the device, at the location of the aforesaid accessory, with a means of detection sensitive to a difference in pressure between the pressurized fluid and the discharged fluid, and placing between the abovementioned reversing gate and the other actuator for which one wishes the fluid to always act in the same direction, in particular the hydraulic motor, an auxiliary reversing means, devised so as to receive a command from the detection means and to automatically couple, as a function of this command, the pipe supplied with pressurized fluid to a same specified coupling of the other actuator, in particular the motor.
In one embodiment of the device according to the invention, the detection means and auxiliary reversing means are combined into a system of four check valves each devised so as to open in one direction and close in the other direction of flow of the fluid. These four valves are then mounted in the manner of a four-diode Graxc3xatz bridge for rectifying an electric current, as explained in detail hereinbelow.
In another embodiment of the invention, the device concerned can comprise, in the guise of detection means, at least one drive gate devised so as to sense the pressure of the pressurized fluid, with respect to that of the discharged fluid, of one of the two pipes, and in the guise of auxiliary reversing means, a gate having two positions, a position for parallel coupling and a position for crossed coupling of the two pipes to the two couplings of the second actuator.
Other details and features of the invention will emerge from the secondary claims and from the description of the drawings which are appended to the present document and which illustrate, by way of nonlimiting examples, particular embodiments of the device according to the invention.